Dr. Tim's One & Only or Bio-Spira contains pure-strain Nitrosomonas + Nitrobacter. Adds them ready-to-grow. Proven to cut cycle to 7-14 days.
A handful of bio-media or substrate from a mature tank seeds your new tank with bacteria. Cuts cycling by 1-3 weeks.
Aquacultured live rock comes pre-seeded. Tank cycles in 7-21 days vs 4-6 weeks with dry rock.
Heat to 80-82°F. Bacteria reproduce 2-3x faster than at room temp.
Dose 4 ppm ammonia (vs 2 ppm). More substrate = more bacterial growth. Don't exceed 5 ppm - bacteria nitrification slows above that.
Products like API Quick Start are weaker than Bio-Spira. Some "instant cycle" products contain heterotrophic bacteria (different species) that crash within days.
Browse all cycling troubleshooting articles. Pair with the cycle ETA calculator + fishless cycle ammonia calculator.